Questions tagged [titration]

A laboratory method to determine the concentration of an analyte in solution. The solution volume plays a key role in the analysis.

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Why does a titration have to be precise?

When we do titrations (w/ phenolphthalein) in lab, I know it's fun to see how close we can get the solution to clear, but why does my teacher place so much emphasis on accuracy and criticize ...
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878 views

Is the amount of substance of acid and base always equal at the equivalence point?

Does the amount of substance of acid always have to equal the amount of substance of base at the equivalence point? I know it "works" for monoprotic acids and monobasic bases, but what if we had a ...
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Redox Titrations Half & Full Equations

I was presented with the following problem and I am finding it difficult to present the half equations for the answers. I managed to produce the half-equation for the Iodine redox. $\ce{2I- -> ...
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A titration mixture having pottasium oxalate and pottasium hydrogen oxalate!

I came across this question, this is how it goes- A solution is prepared by dissolving a solid mixture of $\ce{K2C2O4}$ and $\ce{KHC2O4}$. A $\pu{10 ml}$ portion of this solution required $\pu{10 ml, ...
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Calculating the pH of soft drink [closed]

Me and my classmates are doing an experiment in order to determine the pH of Sprite. We are going to conduct a titration with NaOH. We are taking under consideration that the citric acid in Sprite is ...
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121 views

How to find pH in the following titration/buffer problem given concentration of base and acid

A $100. \text{ mL}$ sample of $0.10 \text{M } \ce{HCl}$ is mixed with $50. \text{ mL of } 0.11 \text{M } \ce{NH3}$. What is the resulting pH? (Kb for $\ce{NH3} = 1.8 × 10–5$) I was thinking more ...
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How to determine which combination of substances will give a buffered solution given target pH and Kb of each substances

What combination of substances will give a buffered solution that has a pH of 5.05? (Assume each pair of substances is dissolved in 5.0 L of water.) (Kb for NH3 = $1.8 × 10^{–5}$; Kb for C5H5N = $1.7 ×...
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How to solve titration problem?

A sample of 40.0 mL of a .100 molar HIO solution is titrated with a .150 molar NaOH solution. Ka for hypoiodous acid = 2.3 x ^ (-11) What is the pH of the solution? I have the following work: As you ...
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148 views

Why is a titration necessary? Why can't we just compare the moles of the acid and base?

For the following question: $\mathrm{1g}$ of $\ce{Mg(OH)2}$ is completely dissolved in $\mathrm{25}$ mL of $\mathrm{0.5}$ M $\ce{HCl}$. This solution is then titrated with $\mathrm{0.1}$ M $\ce{NaOH}...
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Dichromate-thio titration

Can dichromate in acidic media be titrated directly with buffered thiosulfate solution using $\ce{H2O2}$ as an external indicator instead of using $\ce{KI}$ which is a standard procedure? $\ce{...
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How would one correct for a blank in a potentiometric titration?

I want to do a potentiometric titration with perchloric acid of a sample consisting of active drug (weak base) and two other components. Based on theory, I already know that these two other components ...
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How to determine the theoretical concentration of the acetic acid solution in mol dm-3 of vinegar

How do you determine the theoretical concentration of an acetic acid solution in mol dm-3 of vinegar that is 5% acetic acid, knowing that the density of vinegar is 1.000g cm-3?
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How do I find the moles of NaOH required to reach the equivalence point? [closed]

For each trial with the unknown acid, calculate the following: a) Moles of $\ce{NaOH}$ required to reach the equivalence point. I need help with part A. I have already solved and figured out the ...
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Diprotic Basic Buffer

So, as part of an experiment, I plan to make a diprotic basic buffer. For a monoprotic basic buffer, I used the standard combination of Ammonia and Ammonium Chloride. However, how can I make a ...
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Color change of potassium permanganate during a titration with Fe(II)

Is it possible for potassium permanganate to have color change (in a titration) from colorless to pink? If so, then in what circumstances (particularly for a titration)? I have been always been taught ...
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Titration of caffeine using Iodine

I was trying to do an investigation on the variation of caffeine content with temperature. I used 6 Lipton yellow label tea bags (black tea) to brew the tea solution. Next, I perform the extraction of ...
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Why, in titration, is universal indicator not commonly used?

My teacher said that we always used indicators such as methyl red, methyl orange, litmus, phenolphthalein, etc. rather than universal indicator. I don't understand why, though, would not universal ...
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Relating pH and buffer capacity

So, here is the equation for a weak acid - strong base pH curve And here is the expression gotten when the derivative of concentration of hydronium ions with respect to volume of base added is ...
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Rationale for titant standardization in alkalinity measurements [ISO 9963-1:1994]

I work in a environmental chemistry laboratory and I will start to do some alkalinity measurements in my project. My research group is pretty big on following any and all standardization possible, ...
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Why rinse flask with distilled water when the flask will be used for storing aliquots of HCl for titration?

In an experiment for standardisation of NaOH with titration, the lab manual instructed students to rinse conical flasks that were supposed to store 1mL aliquots of hydrochloric acid with distilled ...
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How can you perform an acid-base titration with antacids if substances, like aluminium hydroxide, are insoluble?

I am trying to perform an experiment in order to determine the efficiency of different antacids. An online search later shows that you add an HCl solution in a solution created with a base/antacid. ...
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Calculate hardness of water

A sample of water has its hardness due to only $\ce{CaSO4}$. When this water is passed through on anion exchange resin, $\ce{SO4^2-}$, the $\ce{SO}$ ions are replaced by $\ce{OH-}$. A 25.0 mL sample ...
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Calculating the pH of the endpoint in a titration of weak acid and strong base

Show that the pH at the endpoint in the titration of $\mathrm{0.100\ mol\ dm^{-3}}$ ethanoic acid with $\mathrm{0.100\ mol\ dm^{-3}}$ sodium hydroxide is 8.72. The dissociation constant Ka of ethanoic ...
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Potassium permanganate to analyze iron compounds [closed]

In my lab, I used potassium permanganate in order to analyze the amount of iron in a compound with iron in the +2 oxidation state using titration. My question is how would this analysis be different ...
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Do Bases and Acids actually react with each other? [closed]

Let's say we have $5$ $\ce{HCl}$ molecules and we dump them into a container full of water. It's a strong acid so all $5$ $\ce{H+}$ ions would react with water and create $\ce{H3O+}$. It reacts with ...
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501 views

What indicators can be used when substituting iodine with other halogens in the Winkler method?

I'm a chemistry student who is doing an investigation with respect to the Winkler method. The Winkler method is one which is used to find the oxygen content in water. Primarily, the halide which is ...
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Redox reaction KMnO4 + FeX [closed]

Today I was conducting a redox titration with $\ce{MnO4}$ and unknown amount of $\ce{FeX}$ which through qualitative observation looked like $\ce{FeO(s)}$. I titrated the $\ce{FeX}$(which was ...
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Buffers: what does the strong base react with?

I am a bit confused on buffers: If I have a solution with a weak acid (say $\ce{NH4}$) and its conjugate weak base ($\ce{NH3}$), I have a buffer solution (in $\ce{H2O}$). $$\ce{NH4 <--> NH3 + ...
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What happens to acids/bases left out overnight?

I conducted a titration experiment a few days back and was unable to neutralize the solution in time, so I had to leave the solutions of HCl and NaOH out overnight in order to use them the next day. ...
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Why is finding [H+] when given [OH-]= 3.57e-5 M wrong when I use -log[OH-]?

Question/Problem I know that [H+][OH-]=$10^{-14}$ And the problem asks to find out the concentration of H+ when the concentration of OH- is $3.57*10^{-5}$M By using the equation above i find that ...
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pH Curve in Acid/Base Titrations

So I came across a question on the equation of the pH curve, and I wanted to know how the user here arrived at the matter balance equation. Any help would be appreciated! Here is the question: The ...
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How to solvethis problem related to redox titration?

A $1.0\ \mathrm{g}$ sample containing $\ce{BaCl2*2H2O}$ was dissolved and an excess of $\ce{K2CrO4}$ solution added. After a suitable period, the $\ce{BaCrO4}$ was filtered, washed and redissolved in $...
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titration of ascorbic acid

In this article. Authors use $\ce{KI}$ in potentiometric titration of ascorbic acid with permanganate and dont describe why! Anyvody know why should we use $\ce{KI}$ in potentiometric titration of ...
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Finding the molarity of an acid in a titration

I was doing a question that asks the molarity of a 10 mL of tartaric acid that is titrated to phenolphthalein endpoint with 20 mL of 1.0 M NaOH. I worked it out by equating the molarity of the NaOH ...
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712 views

Estimation of CO2 by titrimetric method using phenolphthalein indicator

We were estimating dissolved $\ce{CO2}$ in water by American Public Health Association (APHA) method. It was a titrimetric method using phenolphthalein indicator. Titrant used was $\ce{NaOH}$ and ...
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How does dilution affect result of titration of jam?

We currently do some pH adjustments of jams (target pH of 3.2) using citric acid, however, when there is a large difference between the starting pH and the target pH this can be quite a time consuming ...
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Deriving the equation for oxygen estimation by Winkler’s method

We were doing $\ce{O2}$ estimation by Winkler's method The procedure and reactions involved in this experiment are: Carefully fill a 300-mL glass stoppered bottle brim-full with sample water. ...
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Use of pipette during experiments for determination of oxygen by Winkler's method

We were performing estimation of $\ce{O2}$ by Winkler's method and we were told by the instructor that while adding $\ce{MnSO4}$ and $\ce{NaOH}$ / $\ce{KI}$ the pipette tip should be well below the ...
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Use of Na2S2O3 before starch in Winkler's method

In Winkler's method why is some amount of $\ce{Na2S2O3}$ added before addition of starch solution turning the deep straw coloured solution pale straw? Is it to generate $\ce{I-}$ ions needed for ...
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What are the reactions occurring during the titration of a carbon dioxide contaminated water sample with diluted sodium hydroxide solution?

During estimation of dissolved $\ce{CO2}$ in water, we took a water sample, added few drops of phenolphthalein and titrated it against dil $\ce{NaOH}$. Questions What are the reactions that happen: ...
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Should the measurement uncertainty be included in the random uncertainty?

So, the other day I was carrying out a titration and got the titres $33.4cm^3$ and $33.3cm^3$. I calculated the random uncertainty to be $0.05cm^3$. Now, the burette itself had an uncertainty of and I'...
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Reaction of sodium hydroxide with ethanol

I am carrying out a titration to determine the solubility of a carboxylic acid in mixtures of water and ethanol. I will be titrating a diluted (previously) saturated solution of water, ethanol and the ...
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How did early chemists measure concentrations and purity?

My chemistry teacher loves going back through the history of famous chemists. This got me wondering how these chemists would first determine the concentration of a sample before they had any other ...
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How to determine the equivalent weight of CO2

We were estimating dissolved $\ce{CO2}$ in water by American Public Health Association method. It was a titrimetric method using phenolpthalein indicator. Titrant used was $\ce{NaOH}$ and analyte was ...
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91 views

Why do we say there's no carbon dioxide present?

Were were estimating dissolved $\ce{CO2}$ in water by American Public Health Association method. It was a titrimetric method using phenolphthalein indicator. Titrant used was $\ce{NaOH}$ and analyte ...
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1answer
687 views

When does phenolphthalein containing solution change colour? [closed]

We were estimating the amount of dissolved $\ce{CO2}$ in water using the American Public Health Association method. It was a Titrimetric Method using phenolphthalein indicator. Titrant used was $\ce{...
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How to quantify caffeine content in coffee?

How do I titrate caffeine from coffee to estimate the percentage of caffeine in coffee? I have tried using iodine solution, sulfuric acid, and sodium thiosulfate to no avail.
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How to find the equivalence point on a graph of an acid-base titration curve? [closed]

Here is the data taken from the lab: Acid pH, Vol (cm3)[ (9.67, 4cm3) (9.08, 8cm3) (8.70, 10cm3) (8.06, 12cm3) (7.93, 13cm3) (4.76, 14cm3) (2.45, 15cm3) (2.23, 16cm3) (2.10, 17cm3) (2.01, ...
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EDTA Titrations

I was doing some questions on EDTA titrations and was wondering how you actually derive the second equation here: $$\begin{align} α_{\ce{Y^4-}} &= \frac{[\ce{Y^4-}]}{[\ce{H6Y^2+}] + [\ce{H5Y+}] + ...
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Why do we titrate from a colourless solution and why should we remove unused sodium hydroxide from the burette as soon as possible?

In my lab we performed an acid base titration, where NaOH was used to titrate a standard solution, potassium hydrogen phthalate (KHP, or $\ce{K+C6H4(CO2H)(CO2^-)}$), using phenolphthalein indicator. ...